Juha Tervala University of Helsinki   Department of Economics, P.O. Box 17, FI-00014 University of Helsinki, Finland ,   juha.tervala@helsinki.fi   http://www.valt.helsinki.fi/blogs/jtervala/           JEL Areas: E : Macroeconomics and Monetary Economics F4 : Macroeconomic Aspects of International Trade and Finance: General